Overview
The Bussmann FRS-R-75 Fusetron is a UL-listed Class RK5 time-delay fuse engineered for industrial, commercial, and institutional electrical systems. With a 75-ampere rating and dual-element, current-limiting construction, the FRS-R-75 provides advanced overcurrent protection in circuits subject to inrush and surge currents from motors, transformers, and other inductive loads. The 600VAC/300VDC voltage rating and rejection-blade design ensure compatibility with standard fuse holders and add an extra layer of safety against cross-installation.
Key Features
- Dual-Element Time-Delay Design: Tolerates brief inrush currents without nuisance trips; delivers 10 seconds minimum time-delay at 500% of rated current.
- Current-Limiting Construction: Limits fault current to 200kA (600VAC) / 20kA (300VDC), protecting downstream components from high-energy arcs.
- Class RK5 Certification: Meets ANSI/UL 248-12 standards; compatible with Class RK5 fuse holders and panelboards.
- Non-Indicating, Rejection-Blade Type: Knife-blade terminal design prevents accidental misfit; fiberglass cartridge body for durability.
- Motor & Transformer Protection: Sized close to full-load amperage, reducing circuit breaker stress and improving blackout prevention on three-phase systems.
Technical Specifications
- Ampere Rating: 75A
- Voltage Rating: 600VAC / 300VDC
- Interrupting Rating: 200kA @ 600VAC; 20kA @ 300VDC
- Fuse Class: RK5
- Type: Time-Delay, Dual-Element, Current-Limiting
- Body Material: Fiberglass
- Terminal: Knife-Blade (Rejection)
- Indication: Non-Indicating
- Dimensions: 1.11 in. diameter × 7.88 in. length
- Time-Delay: 10 seconds minimum @ 500% rated current
- Series: Fusetron FRS-R
- Certifications: UL 248-12, CSA, CE
- Manufacturer: Eaton Bussmann
Typical Applications
The FRS-R-75 is specified in motor branch circuits, transformer-fed distribution systems, and general-purpose industrial feeder protection. Its time-delay characteristic makes it suitable for circuits with predictable inrush events—such as 3-phase motor starters, soft-starters, and VFD-fed loads. It also protects lighting panels, meter circuits, and other load centers in commercial and institutional facilities where surge tolerance and current limitation are critical for equipment longevity.
Compatibility & Replacements
Compatible With
- Class RK5 UL-listed fuse holders and base-block holders
- Standard industrial panelboards and distribution cabinets
- Motor control centers (MCCs) with Class RK5 cavities
- Transformer protection circuits rated 600VAC or lower
- Three-phase motor branch circuits (NEMA MG-1, NEC Article 430)
Replaces / Drop-In Replacement For
- Mersen/Ferraz Shawmut TRS-R-75
- Littlefuse FLSR-75
- Legacy Cooper Bussmann FRS-R-75 units
Works With
- Single-phase and three-phase circuits at 600VAC maximum
- DC circuits up to 300VDC
- Motor starters, contactors, and soft-starter-protected circuits
- Transformer secondaries and distribution feeders
- Legacy and modern panelboards designed to accept rejection-blade cartridge fuses
